Highwall mining is a method for mining coal from exposed seams. In this method of mining, an unmanned cutter module is driven underground and operated in front of the highwall. The highwall mining machine stands on the pit floor or on a bench, directly in front of the exposed seam and makes long parallel rectangular drives into the coal seam.
A remote-operated cutter module is pushed into the seam by a string of push beams (unmanned coal-conveying elements) that transport the mined coal back to the entry of the drive onto a stockpile. The whole mining cycle is completed by a three- or four-man crew, with no personnel going underground at any time.
Current highwall miners use fiber optic gyros to determine the position and orientation of the cutter module relative to the highwall miner frame. Accurate information regarding the position of the cutter module is needed so the cutter module can follow the coal seam. Accurate information is also needed to prevent cutting into previously mined drives, optimize pillar width, and optimize coal recovery. Some highwall miners use radiation sensor to help keep the cutting module in the seam.
The highwall miner is configured to add box-like sections called pushbeams to form a continuous string that connects the cutter module to the highwall miner. As coal is mined by the cutter module, it is collected into the string of push beams and conveyed back to the highwall miner where it can be piled for collection by loaders and trucks. A stack of dozens of pushbeams is provided to the highwall miner. Push beams are added to the string as the cutter module gets deeper and deeper into the coal seam. The push beam string and cutter module can penetrate as deep as 300 m into the coal seam.
A highwall miner typically provides pressurized hydraulic fluid and water to the power head and cutter module. The hydraulic fluid provides power for the cutter module while the water cools the cutting bits and flushes material away from the cutting bits.
Providing hoses for hydraulic and water to the power head and cutter module is a challenge because push beams are continually added as the cutter module penetrates into the coal seam. To solve this problem, a large reel is mounted to the highwall miner frame. The hydraulic fluid and water lines are collected into an armored chain that is called the hose chain.
If a system that can provide information on the position and orientation of the cutter module is to be used, there must be a robust way to route the lines associated with the system from the highwall miner to the power head and cutter module.
Mining machines have typically used radio waves to communicate between the base machine and the cutter module. Tunnel boring machines have used a laser beam fixed to a known reference point that transmits light to a reflector mounted on the boring machine. Such a system only works when cutting a straight bore and is not suitable for a machine that must follow an undulating coal seam.
U.S. Pat. No. 5,110,189 to HAINES; MARVIN L. et al., issued May 5, 1992, entitled “Redundant remote control system used on a continuous miner and method of using same,” discloses use of a fiber optic line for communicate between a mobile frame assembly and a material dislodging means. However, the fiber optic cable is configured to provide communication and does not supply strain information relating the shape of the fiber optic cable.